One of the world’s top marathon runners has been given a six-year ban from the sport after submitting a fake prescription to attempt to explain a positive drug test.

Ruti Aga, who won the Tokyo Marathon in 2019, returned a positive test for the banned substance methylprednisolone, a steroid which is used to reduce pain, after winning a half-marathon in China in March.

The Ethiopian claimed she had been prescribed the drug to treat a knee injury which she had been suffering from since April 2015.

But an investigation into her test by the Ethiopian Anti-Doping Authority revealed that the prescription she submitted came from a medical clinic which did not actually exist, and was issued to her by a family member who had “no medical registration with the relevant authority”.

Aga was charged with violating three anti-doping regulations but did not respond to the charges before the deadline, which could potentially have taken a year off her suspension if she admitted the breaches. The ban was therefore issued without a hearing.

The Athletics Integrity Unit (AIU) said on Thursday that it had banned Aga for two years for the positive test and a further four years, to be served consecutively, for “tampering” with the investigation.

Aga attempted “to mislead the investigation by providing false information in an interview” in April and produced a “forged/manipulated document” in May, according to the AIU’s press release on the case.

The 32-year-old was ranked 11th in the world at the time of testing positive and as well as claiming the Tokyo title in 2019 had four top-three finishes at World Marathon Majors.

The AIU’s chief executive, Brett Clothier, said: “Protecting clean competition takes resources, but this case sends a clear message: attempts to cheat will be exposed”.